1.2 kV fast recovery diode for PFC and flyback clamp circuits
The STTH212S is a 1.2 kV, 2 A fast-recovery rectifier from STMicroelectronics, housed in a DO-214AB (SMC) surface-mount package. Its 75 ns reverse recovery time (trr) places it in the fast-recovery class, suited for continuous-conduction-mode PFC boost stages, flyback snubbers, and high-voltage freewheeling diodes where switching losses matter.
Switching speed determines the snubber budget
The 75 ns trr is the headline switching parameter. In a 100 kHz PFC stage, the turn-off loss scales with trr and the peak reverse voltage; a 75 ns diode lets you keep the snubber RC values lean compared to a 200 ns part. The forward drop is 1.75 V at 2 A, so at full rated current the conduction loss is 3.5 W — the SMC footprint's thermal pad area on the PCB sets the junction temperature margin.
Package and thermal routing for SMC
The DO-214AB (SMC) package is a standard surface-mount outline with a cathode tab that transfers heat to the board copper. For 2 A continuous at 1.75 Vf, the PCB copper area under the tab should be at least 30 mm² per layer to keep Tj below 175 °C. The SMC body is larger than the SMA sibling, so the pad layout follows the JEITA / IPC-7351B SMC footprint.